In a collaborative effort, scientists from NCDC, the Cooperative Institute for Meteorological Satellite Studies–Wisconsin, and the Cooperative Institute for Climate and Satellites–North Carolina summarized the current state of scientific knowledge regarding observed and projected changes in weather and climate extremes along with their impact on air and water quality in an article entitled “Changes in Weather and Climate Extremes: State of Knowledge Relevant to Air and Water Quality in the U.S.” published in the Journal of the Air & Waste Management Association.

According to the scientists, heat waves, droughts, wildfires, cold waves, snowfall, and flooding can all affect air and water quality. During heat waves, the air becomes stagnant and traps emitted pollutants, often resulting in increases in surface ozone. Heat waves and drought also dry out vegetation and provide more fuel for wildfires whose smoke is a serious medical hazard. One type of cold wave also allows air pollution to accumulate. And, severe snow storms that knock out electricity can indirectly lead to more air quality problems as people use wood and coal burning stoves, fireplaces, and gas or diesel generators to stay warm.

Floods resulting from increases in heavy precipitation events or from snowmelt can cause combined sewer overflow systems, which are designed to discharge excess wastewater when under extreme duress, to overflow more often into nearby lakes, rivers, or other bodies of water, causing water quality challenges in these typically urban areas. Flooding of industrial areas or agricultural chemical storage locations can cause chemicals to move into nearby watersheds, also degrading water quality and even contaminating some residential areas. Low water levels due to drought can also contribute to deteriorated water quality.

The scientists are highly confident that the United States will see increases in heat waves, decreases in cold waves, and increases in heavy precipitation events in the future. The ramifications of all these changes on air and water quality are complex but important to incorporate into current and future planning efforts.